In optical information transmission, it is essential that the transmission losses are small, both in the different parts of the transmission system and in the coupling between these parts. Waveguide components of the kind mentioned for such systems are known, and in them the orientation of the single crystal body in relation to the crystalline structure is such that the attenuation and dispersion of the light in the waveguides are small. In order that the components will also have small coupling losses, the end surfaces of the body are carefully polished, and this makes the production of the components complicated. Waveguide components are also known where the end surfaces of the body are cleavage surfaces, which gives small coupling losses. The latter components are produced in a simple way, but the orientation of the single crystal body in relation to the crystalline structure is such that large losses are obtained in the waveguides. These components are therefore not usable in many applications.